Crohn’s Disease, Blau Syndrome, and Yao Syndrome are distinct yet interrelated inflammatory disorders that share involvement of the NOD2 gene and overlapping immune pathways.

Crohn’s Disease is a Multifactorial Autoimmune Disease that shares features of both Autoimmune and Autoinflammatory Disorders. It most often presents in early adulthood, with a median age of onset between 20–30 years as reported by The Crohn's & Colitis Foundation, but is possible at any age. It primarily affects the gastrointestinal tract and causes chronic inflammation, pain, and other systemic symptoms.

 

Blau Syndrome, by contrast, is a Monogenic Autoinflammatory Disease caused by autosomal dominant NOD2 mutations. It presents with pediatric onset (typically before the age of 4). It is characterized by a triad of granulomatous arthritis, dermatitis, and uveitis.

 

Yao Syndrome is a Genetically Translational Disease that is linked to specific NOD2 variants. While it usually appears in adulthood, pediatric cases have been reported (especially with variants in exon 4). Yao Syndrome causes episodic systemic inflammation characterized by fever, rash, arthritis, gastrointestinal involvement, and sometimes serositis such as pericarditis or pleurisy.

 

While all three disorders involve immune dysregulation and inflammation; they differ in genetic inheritance, age of onset, and primary organ systems affected.